Apparatus for maximizing memory density within existing computer system form factors

ABSTRACT

A system includes a memory module formed of a first portion having a first side that directly connects to a mount in the system, which first side is of a first length; and a second portion having a second side, which second side is of a second length, the second length being greater than the first length. The second side may comprise an arcuate form or a plane that is different from the plane of the first side. Each of the first and second portions is used for affixing a memory element.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to memory modules. Moreparticularly, the present invention relates to memory module formfactors that maximize memory density.

2. Description of Related Art

One aspect of the evolution of computer systems is that operatingsystems and software have become more memory-intensive. In fact, thisparticular trend has become so marked that the memory industry has had avery difficult time keeping up with the demand, both from a supply anddevelopment standpoint.

Dynamic Random Access Memory (DRAM) semiconductor chips are the primarycomponents used in memory systems. DRAM's are generally made usingcomplimentary metal oxide silicon technology ranging from 0.8 to 0.3microns in size, with the smaller sizes becoming increasingly prevalent.

While DRAM's have been getting smaller in size, their density has beenincreasing rapidly. For example, several years ago, 1 Mb and 4 Mb DRAMchips were standard. Today, 16 Mb chips are standard; 64 Mb chips are onthe horizon; and 256 Mb and 1 Gb chips are being developed and made.

Also, DRAM packaging has been evolving. Several years ago, memory waspin throughhole packaged. Today, with the common use of surface mounttechnology, small outline integrated circuit (SOIC), thin small outlinepackage (TSOP), and like configurations are most common.

Memory modules serve at least two functions. One function is to makeDRAM's compatible with the system bus organization, that is, reflectiveof the system designer' desire to match the processor bus size. Second,memory modules allow for easy upgrades.

Today, memory modules come in four basic types: one-byte modules (30-pinsingle-in-line memory modules (SIMMS), four-byte modules (72-pin SIMMsor 72-pin small outline, dual in-line memory modules (SODIMMs),eight-byte modules (168-pin DIMMs), and custom modules (e.g., HP 9000workstation memory). SIMMs were first developed by Wang in themid-1970's in conjunction with Molex, the connector supplier for Wang's“office assistant” word processor. While SIMMs have, generally, 30 or 72contacts that are the same on both sides of the “card,” DIMMs have two(dual) rows of contacts, one row on each side of the card. With theadditional pins, a computer can retrieve information from DIMMs 64 bitsat a time instead of the 32 or 16-bit transfers usual with SIMMs.SODIMMs have 72-pins, making them relatively compact and thusparticularly well suited for memory expansion in portables.

Notwithstanding all of the foregoing developments, there still remainsan urgent need to continue to develop methods and apparatus formaximizing DRAM density within the space constraints of existingcomputer systems. To the extent this has been attempted or effected bymanipulating the form of memory modules, system designers have mademodules higher or taller. In many systems there is a limit as to howhigh or tall such a module can be, limiting usefulness of this approach.It is a shortcoming and deficiency of the prior art that heretoforethere has not been envisioned a way to maximize DRAM density in systems,by manipulating the form of memory modules in a way that does not makethem too tall to fit in many systems.

SUMMARY OF THE INVENTION

The present invention overcomes the shortcomings and deficienciesmentioned above by providing a system including a memory module formedof a first portion having a first side that directly connects to a mountin the system, which first side is of a first length; and which memorymodule is also formed of a second portion having a second side, whichsecond side is of a second length, the second length being greater thanthe first length.

In a preferred embodiment of the present invention, the second sideextends beyond the first side in two directions, thereby forming a“T-shape”.

In alternative embodiments of the present invention, the second sidedefines a nonlinear element, such as an arc.

The present invention also provides a method for increasing memorycapacity in a system, which method includes the steps of providing amodule with an area that extends beyond its connector footprint,mounting memory elements on the module so that at least a portion ofmemory is disposed in the area that extends beyond the module'sconnector footprint, and connecting the memory module with memorymounted thereon to the system.

Accordingly, an object of the present invention is to provide simplemethods and apparatus for maximizing DRAM density within the spaceconstraints of existing computer systems.

Another object of the present invention is to introduce new forms ofmemory modules, so there is greater choice in how memory can be disposedin systems which use the memory.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had byreference to the following detailed description when taken inconjunction with the accompanying drawings wherein:

FIG. 1 is a simplified, partially cut-away drawing of a computer housingin which a memory module according to the teachings of the presentinvention is installed;

FIG. 2 is a plan view of the memory module of FIG. 1;

FIG. 3 is a plan view of a first alternative embodiment of a memorymodule according to the teachings of the present invention;

FIG. 4 is a plan view of a second alternative memory module according tothe teachings of the present invention; and

FIG. 5 is a perspective view of a third alternative memory moduleaccording to the teachings of the present invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE PRESENTINVENTION

Referring now to the drawings wherein like or similar elements aredesignated with identical reference numerals throughout the severalviews, and wherein the various elements depicted are not necessarilydrawn to scale, and in particular, to FIG. 1, there is shown a preferredembodiment of the present invention in the form of a memory module 10.Memory module 10 is shown in FIG. 1 to be mounted in a slot 12, and heldby retaining arms 14, 16, on a board 18 in computer system 20. Computersystem 20 in FIG. 1 is depicted as a housing 22 that is partially cutaway to show module 10. It should be understood by the reader hereofthat a number of conventional details are not shown in this FIG. Forexample, housing 22 would likely be formed in parts to allow readyaccess to internal components; those parts are not depicted.Furthermore, computer system 20 would also likely comprise a processor,power supply, hard drive, and other conventional components; thosecomponents are not depicted either. The instant invention resides in theform of memory modules; that being so, aspects of system 20 that do notdirectly affect, or are not directly involved in the operation of themodule 10, which aspects would not help clarify or explain the instantinvention, are not depicted herein. In general fact, conventionalcomputer systems generally include slots and retaining arms for themounting of memory modules. A memory module according to the teachingsof the present invention should be understood as being readilyinsertable into and retainable by such “prior art” slots and arms.

Continuing to refer to FIG. 1, there is, however, one aspect of theinstant invention that should be noted here: that aspect being that themodule 10 readily fits within the confines of the housing 22. Morespecifically, in FIG. 1 the housing 22 may be seen to have a height “h.”The memory module 10, on the other hand, has a height “m,” taking intoaccount its elevated status in the slot 12, with height “m” clearlybeing less than “h.” In the evaluation of computer systems, especiallyinsofar as that evolution has led to development of notebook computers,which have very small heights “h's,” there is less and less “realestate” or space for conventional memory modules for memory elements. Asthose skilled in the art are well aware, conventional memory modules arerectangular, with the length of the module base being fixed by the sizeof conventional slots into which the modules are inserted. Thus, if itis desired to increase the number of memory elements associated with aconventional memory module, the conventional memory module must be madetaller. Once again, the value of “h” is a limit on such growth. In thecase of notebook and subnotebook computers, “h” can be quite small,greatly limiting the amount of memory density within the system.

Referring now to FIG. 2, the memory module 10 can be seen in greaterdetail. In very general terms, it can be seen that memory module 10 hasan increased amount of real estate relative to prior art memory modules,without an overly limiting increase in height, by comprising a firstportion 24 and a second portion 26. The first portion is likeconventional memory module, insofar as it is rectangular, with a base 28generally equal in length to the slot 12 in which it is inserted. Thesecond portion 26, however, constitutes a dramatic departure from theprior art. The second portion 26 projects beyond the sides 30, 32 toeffectively form a broad “T-shaped” element. The two projecting portionsof that “T-shaped” element, portions 34, 36, comprise areas on whichmemory elements (for example, elements 11A and 11B) can readily bemounted, and yet which areas do not fully project above the firstportion 24 so as to increase the height of the memory module 10.

As an aside, also shown in greater detail in FIG. 2 are arms 14, 16.Arms 14, 16 should be recognized as rotatably mounted at each end of theslot 12. When a module is not in slot 12, the upper portions of the arms14, 16 tilt away from the slot 12. If and as a memory module, e.g.,module 10, is inserted in the slot 12, the base 28 of the module willpush the bottom portions of the arms away from the slot, causing theupper portions of the arms to swing into the slot and module, and tointeract with the module in any number of known ways, to facilitatealignment and/or retention of the module 10 in slot 12.

Referring now to FIG. 3, there is depicted an alternative form of amemory module according to the teachings of the present invention. Thisembodiment differs from the embodiment of FIGS. 1 and 2 insofar as ithas only a single projecting portion 34, and not also a secondprojecting portion 36. Still, it should be appreciated that this form ofmodule offers additional real estate for the mounting of memory element,which additional real estate does not effectively increase the height ofthe module.

Referring now to FIG. 4, there is depicted yet another alternative formof a memory module according to the teachings of the present invention.In that FIG., it can be seen that the module is not “T-shaped” becausethe upper edge of the second portion is non-linear—in fact, it isarc-shaped. In broad terms, the present invention is simply a form ofmemory module where real estate is increased by means other than astraight, direct increase in height. In the embodiment of FIG. 4, thereis an increase of real estate both to the sides and upward; the increaseis clearly not 100% tied to an increase in height, however, asexclusively taught by the prior art.

Referring now to FIG. 5, there is yet another alternative embodiment ofthe present invention. This embodiment differs from previously discussedembodiments insofar as second portion 26 may be seen to lie, in part, ina different plane from first portion 24 (in fact, second portion 26 liesin three planes, only one of which is the plane of first portion 24).This embodiment, although not “flat” like previous embodiments, offersgreater real estate for mounting memory elements without requiring anincrease in height. It can also, in certain circumstances, make the bestuse possible of constrained space.

Looking at the instant invention in another way, the instant inventioncomprises a memory module with an area that extends beyond its connectorfootprint. Couched in method terms, the instant invention is practicedwhen memory elements are mounted on such a module so that at least aportion of the memory is disposed in the area that extends beyond themodule's connector footprint, and when such a memory module is connectedto a computer system.

Based upon the foregoing, those skilled in the art should now recognizeand appreciate how the present invention effectively introduces newforms of memory modules, and how the present invention also providessimple methods and apparatus for maximizing DRAM density within thespace constraints of existing computer systems. Towards this end, thoseskilled in the art should also readily understand and appreciate how theadvantages of the present invention can be maximized by use of SOIC(small plastic dual in-line packages, usually with “gull wing” feet,designed for surface mounting) and SOJ (“Small outline, J bend”—i.e., anSOIC package with j-bend leads) packages. Being “small outline”packages, they inherently take up less precious real estate on themodule. Those skilled in the art should also readily understand andappreciate how the present invention offers a module designer a greaternumber of options regarding buffer placement on modules, which followsalso from the greater amount of real estate available.

Although preferred embodiments of the method and apparatus of thepresent invention have been illustrated in the accompanying drawings anddescribed in the foregoing detailed description, it will be understoodthat the invention is not limited to the embodiment disclosed, but iscapable of numerous rearrangements, modifications and substitutionswithout departing from the spirit of the invention as set forth anddefined by the following claims. For example, while the preferredembodiments depicted and described herein have been discussed as having“height” limitations, it should also be understood that they could bedisposed in systems in other than “standing up” attitudes, which wouldeffectively impose what would be more accurately referred to as “length”limitations. Other attitudes are possible. Still, the fact remains thatevolving computer systems include less and less space for memorymodules, and such modules can grow more effectively in more than one,rather than merely one, direction.

What is claimed is:
 1. A system including a memory module, said modulehaving a plurality of memory elements, the module comprising: a firstportion having a first side and a first area, said first side fordirectly connecting to a mount in the system, which first side is of afirst length; and a second portion having a second side and a secondarea, which second side is of a second length, the second length beinggreater than the first length, said second side defining an arc; whereinat least one of said plurality of memory elements is affixed to at leastone of said first area and said second area.
 2. The system as recited inclaim 1, wherein said second side is at least generally parallel to saidfirst side, and wherein said second side extends beyond said first sidein at least one direction.
 3. The system as recited in claim 2, whereinsaid second side extends beyond said first side in two directions,thereby forming a “T-shape.”
 4. A computer system comprising: a memorymodule, said memory module having a plurality of memory elements; saidmemory module including a first portion having a first side and a firstarea, said first side for directly connecting to a mount in the system,said first side is of a first length; and said memory module furtherincluding a second portion having a second side and a second area, saidsecond side is of a second length and defines an arc, the second lengthbeing greater than the first length; wherein at least one of saidplurality of memory elements is affixed to at least one of said firstarea and said second area.
 5. The computer system as recited in claim 4,wherein said second side is at least generally parallel to said firstside.
 6. The computer system as recited in claim 4, wherein said secondside extends beyond said first side in at least one direction.
 7. Thecomputer system as recited in claim 4, wherein said second side extendsbeyond said first side in two directions, thereby forming a “T-shape”.8. A computer system comprising: a memory module including a firstportion and a second portion; said first portion of said memory modulehaving a first side and a first area, said first side for directlyconnecting to a mount in the system, said first side being of a firstlength; said second portion having a second side and a second area, saidsecond side being of a second length and defining an arc, said secondlength being greater than said first length; and a plurality of memoryelements affixed to at least one of said first area and said secondarea.
 9. The computer system as recited in claim 8, wherein said secondside is at least generally parallel to said first side.
 10. The computersystem as recited in claim 8, wherein said second side extends beyondsaid first side in at least one direction.
 11. The computer system asrecited in claim 8, wherein said second side extends beyond said firstside in two directions, thereby forming a “T-shape”.